Vertically aligned metal oxide nanostructures (e.g., wires, needles, pillars and trees) of CuO, PdO and NiO were synthesized on several substrates (e.g., Si and ITO (indium tin oxide)) using a high-pressure (∼Torr) microplasma-based growth technique. Organometallic precursors were dissociated in the hollow cathode region of a supersonic plasma jet creating a directed flux of metal species (e.g., atoms, metastables, etc) which react with an oxygen background to form crystalline metal oxide films having a variety of nanomorphologies. Spiral-like growth fronts were seen in some cases for CuO, suggesting that nanowire growth may involve screw dislocations. Large area, nanowire films >1 cm(2) with good adhesion and electrical connection to ITO substrates were deposited by raster-scanning a single jet. Details of the microplasma operation, the dynamics of the growth process and the resulting materials are discussed.